Exhaust aftertreatment systems are used to receive and treat exhaust gas generated by engines such as IC engines. Conventional exhaust gas aftertreatment systems include any of several different components to reduce the levels of harmful exhaust emissions present in exhaust gas. For example, certain exhaust aftertreatment systems for diesel-powered IC engines include a selective catalytic reduction (SCR) system which includes a catalyst formulated to convert NOx (NO and NO2 in some fraction) into harmless nitrogen gas (N2) and water vapor (H2O) in the presence of ammonia (NH3).
Generally, a reductant such as a diesel exhaust fluid (e.g., an aqueous urea solution) is inserted into the aftertreatment system as a source of ammonia. The reductant facilitates the decomposition of the constituents of the exhaust gas by the catalyst included in the SCR system. The delivery of the reductant into conduits of the aftertreatment system is generally assisted by the exhaust gas flow to achieve efficient mixing of the reductant with the exhaust gas and reduce reductant deposits. To enhance mixing of the reductant with the exhaust gas, mixers are often placed in the flow path of the exhaust gas. However, the mixers also serve as sites where reductant deposits tend to form and build up over time. Such reductant deposits can clog the mixers, which can reduce mixing efficiency as well as reduce flow rate increasing backpressure on the exhaust gas flowing through the aftertreatment system.